Table 1.
World Health Organization (WHO) 2010 classification of neuroendocrine tumours.
| Grade | Mitotic count (mitoses/ 10 high power fields) | Ki-67 index | WHO/ENETS nomenclature |
|---|---|---|---|
| Grade 1 | <2 mit/10 HPF | <3% | Neuroendocrine tumour |
| Grade 2 | 2–20 mit/10 HPF | 3–20% | Neuroendocrine tumour |
| Grade 3 | >20 mit/10 HPF | >20% | Neuroendocrine carcinoma (large cell or small cell type) |
| Mixed adenoneuroendocrine carcinoma | |||
| Hyperplastic and preneoplastic lesions | |||
Mit, mitoses; HPF, high power fields; WHO, World Health Organization; ENETS, European Neuroendocrine Tumour Society.